Revert "Harden gemini vision JSON recovery"

This reverts commit 513199f426.

TODO.md

@@ -655,22 +655,6 @@
 - If behavior in the browser does not match the latest backend/frontend code, the first assumption should be stale frontend assets until proven otherwise
 
 ## Recent Change Log
-- Date: `2026-03-17`
-- What changed:
-  - Reduced Gemini Vision batch size from `6` to `4` so each model response carries fewer recommendation objects and is less likely to be truncated mid-JSON.
-  - Tightened the Gemini Vision prompt to ask for shorter Korean reasons and compact JSON-only output.
-  - Lowered Gemini Vision `maxOutputTokens` and added partial JSON recovery so already-complete recommendation objects can still be salvaged when the model output is cut off before the final closing braces.
-  - Added unit coverage for truncated Gemini Vision JSON recovery.
-- Why it changed:
-  - The user-provided log `ai-media-hub-2026-03-17T07-29-44-949Z.log` showed that visuals were prepared successfully, but every batch failed with `gemini vision JSON extraction failed: no complete JSON object found ...`.
-  - The failure pattern indicates output truncation rather than missing thumbnails or preview frames.
-- How it was verified:
-  - `pwsh -NoProfile -File scripts/selftest.ps1`
-  - added Go tests for partial Gemini JSON recovery behavior
-- What is still risky or incomplete:
-  - If Gemini returns severely malformed output before even one full recommendation object closes, the parser still cannot recover useful results from that batch.
-  - Smaller batch size improves reliability but can increase total Gemini round trips and latency on some searches.
-
 - Date: `2026-03-17`
 - What changed:
   - Fixed a search-budget regression where source collection could consume the full `SearchService` deadline and leave no time for Envato / Artgrid enrichment, causing Gemini to see only missing or low-value visuals.